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By S Pollak, A Amon

This paper describes the current and finished design work which has been performed for shallow rock station caverns for New York CityÆs first new subway construction in 60 years. A new robust, sophisticated, design procedure has been developed for two up to 30 m wide caverns, with overburden of less then 12 m, and rock cover to span ratios (C/S) in the order of 0.25. The design is based on empirical input parameters like the Q-value, rock mass rating (RMR) values, rock mass class after Cording (1984), cover to span ratios, which have been validated by the use of structural computer models as well as two- and three-dimensional numerical discontinuum models. The design approach is a staged approach using first principles, empirical models and non-linear FEM and DEM models. In addition, the paper describes the factors and circumstances why shallow caverns have been selected instead of cut-and-cover structures and why all the underground station structures have been developed as drained structures.

Jan 1, 2008

By J Szymanski, Y Hu

Excavation engineering involves complex processes for primary and secondary extraction of materials. The shovel excavators bear varying mechanical energy input and stress loading across the working bench during excavation. These varying mechanical energy input and stress loading effects cause significant wear and tear and fatigue failure in equipment components. These effects further result in unplanned downtimes, reduced efficiency and high production costs. In addition, the mechanical and electrical control systems must be operated in efficient profiles to generate maximum outputs and efficiency from these excavators. Efficient technologies are therefore required to solve these problems in order to reduce production costs and increase efficiency. In this paper, the authors develop a rigorous simulator for a hydraulic shovel in a surface mining environment. The finite element model is used to capture the stress profile within the shovel components during excavation, such as, the bucket, stick and boom assemblies. The profiles are classified into normal, critical and extreme ranges, with appropriate corrective measures to avoid extreme loading conditions. The loading capability of shovel excavators can be examined by assessing its structural strength against all possible maximum loads working on the equipment. The dynamic model is used to define efficient profiles of the critical structural components of hydraulic shovels during digging operation. This assessment is used to locate the maximum possible loads and the critical sections of the structures. The method presented in this paper forms the basis for developing comprehensive simulator models for efficient shovel operations in constrained mining environments.

Jan 1, 2003

By LefTvre Y

In May 1991, AZSA commissioned a new conventional Cell House. This paper focuses on the major improvements introduced in the design and the construction of the equipment, machinery and control. An effective control system together with good reporting and routine operation has resulted in quality control of the Cell House at the highest possible level. Consequently the monthly current efficiency consistently averages above 93 per cent with a total energy usage of 3000 AC kWh/t of cathode zinc. The new concept for the year 2000 and beyond is introduced.

Jan 1, 1993

By P Licence, M Stevens, P Atkinson, J L. Mauk

The Rahu and Ascot epithermal Au-Ag prospects are two km north of the Karangahake deposit in the Hauraki Goldfield, and all occur in an approximately 6 km2 north-south elongated magnetic æquietÆ zone. The prospects are hosted by andesitic flows, lithic-crystal tuffs and local sedimentary rocks; local silica sinter occurs at Ascot. These host rocks are intensely altered by quartz, adularia, albite, chlorite, pyrite, illite, interstratified illite-smectite and calcite. Several minerals show zoned distributions, such as widespread adularia that overlies more localised and deeper albite. Illite is the only dioctahedral phyllosilicate in several drill holes, but elsewhere it forms a shallow carapace underlain by interstratified illite-smectite with 50 to 90 percent illite. Veins are common with quartz dominating near the surface and calcite becoming more abundant at depth. Local laumontite-calcite veins also occur. Pseudosecondary and secondary fluid inclusions in quartz and calcite at Rahu and Ascot have homogenisation temperatures (Th) that range from 162¦ to 268¦C and 128¦ to 243¦C, respectively. Most inclusions have trapped dilute fluids with salinities of less than 1.9 weight percent NaCl equivalent, but 20 percent of the inclusions have salinities of 2.0 to 10.5 weight percent NaCl equivalent. Calculated paleowater table elevations suggest that the water table at Rahu occurred at 440 m above sea level (asl). At Ascot, silica sinter formed from discharging geothermal fluids (=100¦C) at the paleosurface at ~135 m asl. However the sinter also contains comb quartz with pseudosecondary inclusions that have a Th average of 229¦C, corresponding to a paleowater table at ~430 m asl during inclusion entrapment. Taken together, these results suggest that the Ascot sinter was buried by approximately 300 m of cover material during a major volcanic or tectonic event, and that subsequent hydrothermal fluids formed veins and alteration at Rahu and deposited comb quartz at Ascot.

Jan 1, 2007

By Jury C. G

A decade of expansion and high production targets have led to changes in the number and structure of the Mount Isa Mines Limited work- force. Falls in labour turnover and absenteeism are correlated with two demographic variables, improved selection and placement procedures and home purchase facilities. Some results of recent population surveys are presented and discussed in terms of future housing needs and potential employment problems encountered by school leavers.

Jan 1, 1974

The purpose of this work is to determine the equilibrium-state of the aqueous-solution which is produced by the leaching processes, including natural weathering of pyrite minerals. The latter can lead to acid-mine-drainage (AMD). The ferric iron species (Fe3+) resulting from bacteria-catalysed oxidation of ferrous iron (Fe2+), in the presence of water and air, is known to bring about steady-dissolution of minerals chalcopyrite (CuFeS2), sphalerite (ZnS), pyrite (FeS2), and so forth. Good-aeration, relatively high-porosity and sufficient bacterial activity tend to promote leaching in waste-rock-dumps. The composition of the aqueous-phase that accumulates in the pore-space (or in open-pits) is of practical interest as it would strongly influence the leaching of both sulfide and non-sulfide minerals. Since the reactions among the various ionic species occur relatively fast, the solution-phase may be regarded as approaching a state of virtual-equilibrium and it is possible to determine by computation the respective concentrations of the many dissolved species. For the Cu-Fe-H-O-S system, these species may include: H+, Fe2+, Fe3+, Cu2+, HSO4-, SO42-, OH-, CuSO4o, H2O, Fe(OH)+, Fe(OH)2+, Fe(OH)2+, Fe2(OH)24+, Fe(SO4)+, Fe(HSO4)+, Fe(HSO4)2+, and Fe(SO4)2-. The aqueous-system which may be constituted from appropriate mole-quantities of H2SO4, FeSO4, Fe2(SO4)3, and CuSO4 is in fact the result of various natural processes (reactions) and due respect must be accorded to the extents of these reactions. The present model computes the equilibrium molalities of the foregoing ionic and neutral aqueous species, using the iterative equilibrium constant method that ensures strict-adherence to charge-balance and elemental molar-balance constraints. The dissolving sulfide-minerals (FeS2, CuFeS2) consume Fe2(SO4)3, H2O, and O2 and yield FeSO4, H2SO4, and CuSO4 while the aqueous-phase tends to become progressively acidic (declining pH) reflecting the gradual increase in the extents of sulfide-dissolution reactions. The equilibrium-state of the solution-phase is computed for specific set of values for the extents of respective reactions. The temperature and pressure of the system are 25¦ C (298.15 K) and 101.325 kPa (1.0 atm), respectively. The mica-like minerals such as the biotite [H2K(Mg,Fe)3Al(SiO4)3] tend to consume much of the H2SO4(aq), with the extracted K+, Mg2+, Fe2+ and Al3+ ionic species accumulating in the solution. The precipitation of the jarosites (potassium, hydronium, or ammonium) contributes to the removal of ferric and ferrous species from the solution-phase. In the present work, the emphasis is on predicting the compositions of the aqueous- and condensed-phases with advancing time or increasing æextent of reactionÆ. The results of such calculations are compared to published data on raw AMD (acid-mine-drainage).

Jan 1, 2008

By S Pfaff, R Rajic

In the case when the number of independent variables is greater, a careful design for carrying out tests has to be made in order to obtain, with the smallest possible number of tests, as much as possible neutral information about the influence of independent variables on the dependent ones. Only on the basis of such design and its statistical analysis it is possible to come to right conclusions about the function of the whole system. The influence of pressure, temperature, humidity and granulation of the coal upon the resistance to pressure and the water absorption of the briquettes has been tested, with the aim to examine how each of the two dependent variables changes depending on the values assumed by any of the four independent variables and which of the mentioned independent variables significantly influences the dependent ones. The full factorial design with 16 experiments and the central composite design with 27 experiments have been applied. The influence of the independent variables upon the dependent ones has been examined by applying the analysis of variance. The influence values of individual factors and their interaction upon the dependent variables have been stated as well as coefficients of curvilinear equation.

Jan 1, 2003

By T Raynlyn, A Edenton, M Adam, R J. Holmes, J R. Manuel, N Ware, R Smyth

Due to ongoing demand and increasing depletion of high-grade iron ore resources from large deposits, Australian iron ore producers are developing smaller size deposits to maintain current export levels. The iron grade, mineralogy, chemical and physical characteristics of iron ore fines being mined from different deposits vary considerably. It is therefore imperative to develop long-term strategies to maintain the quality and consistency of iron ore fines while moving to a larger diversity of smaller deposits. Blending is a common practice in sinter plants as it is almost impossible to produce a high performance sinter mixture displaying the required characteristics from one single ore. Blending is also one of the most effective options being used by iron ore producers to ensure the long-term stability of their products while increasing production. When designing a blend, the blend components are selected to support each other to achieve the required overall balanced metallurgical performance of the final product at a relatively low cost. To do so, a fundamental understanding of the key characteristics of iron ore fines and their potential impacts on the iron ore sintering process and sinter quality are required. In this paper, the sintering process and sinter structure have been analysed and the key factors affecting the sintering performance of iron ore fines, including productivity and quality, identified. Under fixed sintering conditions, the granulation efficiency, nuclei stability and the volume and properties of the primary sinter melt are believed to have important impacts on both sintering productivity and sinter quality. Discussion is then focused on the effects of ore chemical, physical and mineralogical characteristics on the key factors identified and in turn the consequences for sintering productivity and sinter quality.

Jan 1, 2009

By P Benjamin, H Bohannan, C Farr

Geoffrey Blainey's historical account of the mining activity on the west coast of Tasmania, æThe Peaks of LyellÆ documents the changes over 130 years of activity in the region. Commissioned by the Mount Lyell Mining and Railway Company, emphasis is placed upon the development of the Mount Lyell Mine in Queenstown. Chapter 19 æWidening HorizonsÆ details the review the Mount Lyell Company undertook in 1904/05 to ensure the future of the operation, following the pessimistic outlook regarding diminishing reserves and poor grade ore. The analogies documented between the Mount Lyell Company at that time, and Gold Mines of Australia 90 years on are remarkable, with both companies demonstrating a commitment to the Mount Lyell area through active exploration, the proactive search for alternative technology and the recognition of the valuable human resource. As Blainey writes (Blainey, 1993), æwith its expanding chemical works, its huge Tasmanian mines, its railways and smelter, its coke works and its mine crusade, Mount Lyell was probably one of the nation's five great industrial companies in 1906 or 1907. This brief phase of industrial and mining expansion had its seed in the threat of extinction . . .Æ After a number of reprieves, the Mount Lyell mine did stop production in 1994, but that only provided an impetus for a review and rebirth.

Jan 1, 1998

By A Richmond

"In some lode-style gold deposits the geological (lithological) uncertainty may have similar economic significance as the grade uncertainty. In the absence of precise knowledge of the deposit geology, geological models of these types of deposits that are used to constrain spatially the estimated (or simulated) grade values may influence significantly the contained metal. Methods for assessing geological uncertainty quantitatively are rarely considered due to their perceived inability to consider exhaustive geological interpretations, and resulting models that often appear geologically unrealistic. Furthermore, should the lodes have been subjected to folding, or where the mineralisation continuity does not follow a planar orientation along strike or down dip, standard methods of variography and interpolation using linear vectors in space often do not provide a good representation of continuity. An alternative approach is to relate spatial samples from adjacent drill holes using an unfolding plane.The paper demonstrates conditional simulation of the geometry and gold grades of a folded lode-style deposit where:simulation of lode geometry considers explicitly the geologistÆs interpretation, andsimulation of gold grade values that consider explicitly the folded nature of the lodes.The results are contrasted to the traditional approach of linear vectors in real space for a single lode interpretation.CITATION:Richmond, A, 2012. Conditional simulation of a folded lode-style gold deposit, in Proceedings Narrow Vein Mining 2012 , pp 149-154 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 26, 2012

This paper will discuss Fordertechnik dawatering screens and their application in process industries. Fordertechnik screens were designed for the dewatering of deslimed, wet fines materials encountered in the mineral beneficiation, sand and coal processing industries. However, these screens have also been used in such industries as municipal waste treatment, paper pulp, chemicals and the food industries. Fordertechnik screens are of simple design and, as a result, offer low capital and maintenance costs. The design is based on the use of twin counter-rotating vibratory motors which provide high frequency, low amplitude linear movement of the screen deck which is essential for high production requirements. Fordertechnik dewatering screens are engineered and manufactured in Australia by Mitchell Cotts Engineering under licence to Fordertechnik GmbH of Mulheim, West Germany

Jan 1, 1984

By Elford H. S, Hughes J. F

The object of this paper is to bring before Members of the lnstitute the very important and much discussed question of scientifically prospecting for ores, oil, coal, etc.The paper is divided into three sections:SECTION l - Description of Geophysical Prospecting methods.(1) Sound-Vibration.(2) Magnetic.(3) Gravitometric.(4) Electrical.(a) Equipotential.(b) Electro-magnetic.(c) Schlumberger.(d) General.SECTION II - General discussion of Cicophysical Prospecting.SECTION III - Appendices.(1) Systematic summary of methods of survey.(2) Table of electrical conductivities.(3) Bibliography.SECTION I - DESCRIPTION O:F GEOPHYSICAL PROSPECTING METHODS.(1) SOUND-VIBRATION.THE transmission of sound waves or vibrations underground will depend on at least three factors: (a) Type of Rock. - Hard, dense rocks wiII transmit sound waves much more quickly than softer, more porous rocks. In the former the speed may be eight times that of the latter.(2) Uniformity of Rock. - Any variation in the texture, hardness, etc, wiII have an effect on and direction of transmission of the waves.

Jan 1, 1927

E Deposit is located at BHP BillitonÆs Area C iron ore operations in the central region of the Hamersley Province, Western Australia. It is hosted by the Marra Mamba Iron Formation, the lowermost unit of the Archaean to Lower Proterozoic Hamersley Group. Mineralisation at E Deposit East is contained within the Mount Newman Member of the Marra Mamba Iron Formation and extends into the lower West Angela Member of the overlying Wittenoom Formation. Use of a combination of geological and geophysical techniques has enabled the geological setting of the deposit to be qualified. Interpretation of detailed mine face mapping, downhole geophysics, geochemistry, geological logging and photography has identified D2- related thrust faulting, with substantial south-over-north displacement. Similarly, in-pit mapping at the nearby C Deposit has revealed intense localised D2 deformation, including overturning and thrust faulting. The interpreted structure illustrates that iron ore deposits in the central Hamersley Province can be intensely deformed and require detailed geological investigation utilising technical data from mapping and drilling to enable the creation of robust grade-models for the mining operation.

Jan 1, 2007

Mine planning studies of iron ore deposits are often based on resource models generated by ordinary kriging. Ordinary kriging aims for local accuracy to minimise the variance of expected estimation error but this is at the expense of reproducing variability of the original sampling data. Hence mine planning studies using kriged models are likely to underestimate product variability, and the required blending and stockpiling capacity to reduce variability to an acceptable level. Instead, conditional simulation models of the main chemical variables in iron ore are able to reproduce likely variability to be encountered during mining and processing. This approach is demonstrated in a case study of the Weld Range bedded iron ore deposit in Western Australia, with a comparison of ordinary kriging and conditional simulation models. Conditional simulation models suggest that, compared with the single ordinary kriging estimation, there is likely to be far greater block variability for iron and impurities, a greater requirement for stockpiling and blending capacity, highest variability in initial years of mining and less variability in later years of mining for deeper ore. The conditional simulations provide a more realistic range of mining outcomes for production of high-grade ore, which may be seven per cent less than in the kriged model, as well as for lower expected project net present value (NPV). In year one, the kriged model is conservative for NPV; however, in later years two to five the kriged model has higher NPV than most conditional simulations, suggesting expected NPV based on the kriged model may not be achieved. For improved decision-making in mine planning, a complete range of possible outcomes from conditional simulations of the deposit should be considered rather than relying on a single kriging estimation that may be an end member case in the range of possible mining outcomes.

Jan 1, 2009

In July 1994 the Premier, John Fahey MP, announced that the New South Wales Government would make available a total of $40 million over six years in new funding for the Department of Mineral Resources. These funds are to be applied directly to the generation of regional geological and geophysical information. The Government's initiative known as `Discovery 2000', is aimed at providing a major boost to the exploration industry. The Government expects new discoveries to be made and new mines to be developed because of the initiative and, perhaps, the first ever commercial oil or gas production in New South Wales. The Government's return will come from increased economic activity, and from the increased royalty return from higher levels of production. Quality information is the key to successful exploration. In the highly competitive business of mineral and petroleum exploration high quality regional geological and geophysical information improve both the efficiency and effectiveness of the area selection or project generation process. Using the `needle in the hay stack' analogy, Discovery 2000 will vastly improve industry's chances of finding the haystacks. It is up to the mineral and petroleum industries to find their respective `needles'. Careful target area selection is probably the most critical factor in mineral exploration. The ability to select the most prospective areas, or to identify prospectivity that others have failed to recognise, can make all the difference between success and failure. Government geological surveys clearly have a crucial role to play in providing the geoscientific information infrastructure that companies must have if they are to make the discoveries this country needs to pay its way in the world. It is the regional information generated by Governments that sets the scene for efficient exploration. This regional information includes regional aeromagnetics and radiometrics and gravity, regional geological mapping and tectonic analysis, and geoscientific databases. The New South Wales Department of Mineral Resources (by various names) has been providing such information for over 100 years and has led the way in many aspects of the generation and dissemination of geological, geophysical and metallogenic Information.

Jan 1, 1995

By M Hassall, E Humphries

Personal risk assessment processes, also known as Take 5 or SLAM (Stop, Look, Assess, Manage) have been utilised in high hazard industries for over 30 years. However, there is limited research to understand if a personal risk assessment process improves safety and health outcomes. The author’s learnings during discussions with training participants in G3/G-MIRM (Risk Management Systems) and G2 (Risk Assessment for Supervisors) courses have provided them with significant insight into understanding if a personal risk assessment process is valued across a number of mining industry organisations. These discussions arise when the four-layer model is presented (Figure 1) where ‘Layer 4’ represents the last resort risk checking activity. In this context, training participants agree that this process has value. However, the consistent opinion is that the personal risk assessment process is not effective, that it is a ‘tick and flick exercise’ and is not achieving the desired outcomes.

Apr 16, 2024

By M Zaluski, D Bless

An innovative, biological treatment process has been designed by MSE Technology Applications, Inc to treat and control acid mine drainage (AMD). A field-scale demonstration is being conducted under the Mine Waste Technology Program using water flowing from a historic mine in Montana. A successful demonstration of an in situ process will allow it to be employed at numerous other abandoned or remote mines, which discharge AMD, an acidic, metal-contaminated water. Conventional treatment methods are costly and are often impossible to use at remote locations. MSEÆs technology uses a biological system to clean up AMD. The In situ Passive Biological Treatment Process utilises nonpathogenic bacteria, which are able to neutralise acidic mine water and remove contained toxic metals. These bacteria live within a series of pile-type reactors inside the mine. The bacteria are fed inexpensive waste products. The resulting discharge is clean water flowing from the mine. This presentation will show that this technology offers a natural cleanup method for the nationÆs numerous abandoned mines. Work on this project was conducted under Interagency Agreement No DW899388-70-01-1 between the US Environmental Protection Agency and the US Department of Energy (DOE), and was performed at the Western Environmental Technology Office through the DOE National Environmental Technology Laboratory (DOE Contract No. DE-AC22-96EW96405).

Jan 1, 2003

Wetherstones gold deposit is located just east of the township of Lawrence, in the Otago District of the South Island, New Zealand. The paper will describe aspects of the mining and exploration history of the Wetherstones gold field, current knowledge of the geology of the deposit, and speculate on possible outcomes of exploration in the modern era.   As at the famed Gabriels Gully situated nearby, most of the Wetherstones gold is/was contained in, or recycled into modern drainages from, the Blue Spur Conglomerate (æBSCÆ). The BSC is the basal member of a wedge of auriferous non-marine sediments of latest Cretaceous age which are tilted against the Tuapeka Fault Zone, a structure of regional dimensions. In particular mineralisation of elevated grade (which cannot yet be reliably estimated) appears to be concentrated in an elongate basement depression (ægutterÆ) of width around 100 m, variable thickness to a few metres, and axial length in excess of 500 m. The gutter plunges from the base of alluvial mining (where it has been partly exploited by underground methods) to depths of more than 100 m, beyond which it remains open and untested.   The prospects for a revival of mining at Wetherstones depend upon confirmation of what is here inferred to exist, and the discovery of additional gold. The economic prospects of the project however are enhanced by what is known or indicated of the geographic location, and anticipated geologic, mining and metallurgical characteristics of the mineralisation, and consequent anticipated environmental management issues.   The recognition of gold contained in pyrite in the BSC represents an upside to project economics which has never previously been evaluated. The Wetherstones Basin covers more than five square kilometres in areal extent. There is no modern exploration record of the majority of this area, leaving open the prospect of the discovery of additional gutters, and primary mineralisation in the underlying schist.   Australasia Gold Ltd has embarked on a program to reassess the potential resources of the Wetherstones gold mineralisation, and to evaluate the feasibility of mining.

Jan 1, 2004

By B Tessier

Checking the quality of a blast may be considered as subjective. Checking this quality will require measuring objective parameters. One of them is the resulting fragmentation of the blasted product. Numerous fragmentation æmeasuringÆ systems have been developed and marketed, based on image-processing. This presentation of FragScan will illustrate advantages and difficulties when using such a system. FragScan is essentially defending a policy of large and representative sampling. The purpose is to show how fragmentation is discriminating both productivity and profit of quarry operations on a blast-by blast basis. The next step will then be to ædriveÆ the blasting process to reach a æbetterÆ fragmentation. Other applications require the fragmentation as an essential result: this is the case for large boulders used in structure-reinforcement. Several case-studies have shown that FragScan can be used for quality-control, checking size-distribution of the product according to the requirements of the end-user. Only clear thinking about the precise use of such a æmeasurementÆ will further the success of this task.

Jan 1, 2001

By Robinson J

A stibnite flotation concentrate from Costerfield in Victoria was found to contain 63.3 g/t An while its sizing distribution indicated that 81.6 per cent of the material was less than 38 ¦m. A 24 hour cyanidation test by a standard bottle roll method recovered 15 per cent of this gold. Pressure cyanidation under conditions of ambient temperature, 40 per cent pulp density, an oxygen pressure of 1000 - 2000 kPa and an initial NaCN concentration of 15 kg/t, resulted in a recovery of 65 pe cent of the gold after only two hours of leaching. Aqueous pressure preoxidation of the concentrate followed by the standard bottle roll cyanidation realised gold recoveries as high as 96 per cent. Conditions of 220¦C, an oxygen pressure of 1000 - 2000 kPa, 16.7

Jan 1, 1991